Like most articles on "Inheritance" this is clueless about providing any "real meaning/understanding". People always take the soundbites (eg. Uncle Bob SOLID) provided as a mnemonic as being the end-all, don't fully understand the nuances and then usually arrive at a wrong conclusion.

LSP (https://en.wikipedia.org/wiki/Liskov_substitution_principle) has to do with behavioural subtyping guaranteeing semantic interoperability between types in a hierarchy. It involves not just the syntax of function signatures but their semantic meaning involving Variance/Invariance/Covariance/Contravariance and their guarantees using an extension to Hoare Logic i.e. Preconditions/Postconditions/Invariants (derived from Meyer's DbC). Thus without enforcing the latter (which is generally done via documentation since there is no syntax for expressing pre/post/inv directly in most languages) the former is incomplete and thus the complete contract is easily missed/forgotten leading to the mistaken belief "Inheritance is bad". The LSP wikipedia page links to all the concepts, the original papers and more for further clarification.

See also Bertrand Meyer's Using Inheritance Well from his book Object Oriented Software Construction, second edition book - https://archive.eiffel.com/doc/manuals/technology/oosc/inher...

Finally see Barbara Liskov's own book (with John Guttag) Program Development in Java: Abstraction, Specification, and Object-Oriented Design for a "correct approach" to OOP. Note that Java is just used as a example language while the principles are language independent.